Help PC Gone to a Crawl

Reboot the PC then see what happens.

I personall wouldn't trust something like Kerish Doctor. I'd remove that, install ClamAV (This can safely run beside McAfee), MalwareBytes AntiMalware and BleachBit, run scans with them, clean anything that ClamAV or MalwareBytes pops up, and selectively clean things with BleachBit. If it's still slow after this, consider running HiJackThis and providing a log.

Maybe your tools like Kerish Doctor caused your troubles. Reboot and run only a minimum on programs, check if the issues persist.
The easiest fix might be to use a recent Windows System Restore point.

Google also suggests that McAfee can slow down PCs a lot.

run panda antimalware, malwarebytes and kaspersky's free rootkitscanner

also, have you met your monthly data cap?

Also one thing you might try is changing DNS like this: https://developers.google.com/speed/public-dns/docs/using

check / reboot your router

The only one of the tools listed so far that I think is important is Malwarebytes Anti-Malware, but that's just my opinion. Install, update, go to the Settings -> Protection tab and turn on Scan for Rootkits, then scan. (These days it mostly updates itself, it will tell you if it's doing that.) Let it delete whatever it detects.

If there's no change and if you are running Windows 10, go to your Settings tab in Windows (Start -> Settings, the gear icon) and open the Updates & Security menu. Open the Updates tab. Is it trying to install an update? In particular, is it trying to install the Features Update 1803? There's a link to your update history, and that will tell you if the Features Update 1803 installed or failed, along with the date. Some systems have trouble with it, and it can make things super slow if it has not installed.

Wait a minute. Is your PC slow now or just your browser?
Have you checked the task manager if any programme or service is using a lot of resources?

if everything is slow, it's probably your HDD. download CrystalDiskInfo and see if there's something wrong.

if it's just internet, clear your windows dns cache: https://www.noip.com/support/knowledgebase/how-do-i-flush-my-windows-dns-cache/
also chrome or firefox: http://www.redsome.com/flush-clear-dns-cache-google-chrome-browser/
http://www.kahunaburger.com/2009/03/18/clear-dns-cache-in-firefox/
change your dns to google: https://developers.google.com/speed/public-dns/

reboot and try again.
if the problem persists it may be your isp not your pc.

If you can't find anything wrong with your computer, it could be a problem with your internet provider or where the data stops at certain spots along the way (I think they are called switches). I had a similar problem a few weeks ago. A lot of sites would not work at all or were extremely slow and I couldn't connect to almost any counter strike servers, but it was not all sites. I had problems with major sites like Google and Amazon, but some other sites would work fine.

I couldn't find anything wrong so I just waited and things were working better the next day. Then they started to go bad again a day or 2 later. After that everything went back to normal and I haven't had a problem since. I figured my ISP was having problems or one of the hops along the path that the data takes to travel around the world had a problem.

You use to be able to figure these things out with a traceroute, but I don't think that works anymore with IPv6. There is probably a new way to do it, but I have not tried to figure it out.

The first thing you should do is check if other devices can connect to the same websites. Do you have a cell phone, laptop, or tablet connected to the same internet? If they can connect without a problem, the issue is with your computer. If they cannot connect, the issue could be with your router or more likely with your ISP.

Will Give this a GO Get Back to ya on THIS Don't Have 29 Dollars Malwarebytes Anti-Malware
The Way live UK & have tried LOOKING for Malware Get a OK. Will Try settings as on win 10
Thanks. Have given you a 💙

I May of COCK UP MY DAUGHTER HAS A NEW IPHONE. IF SHE CONNECTS & SHE KNOWS PASSWORD. WI-FI COULD ThIS BE THE PROB???

Did you get one of the new cryptominer steam games?

MacAfee. There's your major problem. You paid for a virus.

Does the problem occur only on the PC? Can you try to connect a phone to your wi-fi and see if it is slowed down too or not? Could be an ISP/line problem.
If you can, try to turn the Wi-fi off and connect the PC with an ethernet cable to exclude a problem with the wifi (if your router has both types of access).
If you can't do that, access the router and see how many devices are connected to your wi-fi and see if there is anything suspicious (more devices than they should be). Since you're there check also the stats of your line and see if it is stable and the values of upload and download are close to the ones they should be or are significantly lower.

Have you checked task manager if some process takes up a lot of your resources?

It could be a lot of things going on or just one. It's really hard to diagnose something like this without more info. I can tell you this though, if you are running active protection with both McAfee and Kerish Doctor you need to disable one. Running more than one program for active protection can cause conflicts.

Just so you are aware even without running more than one active protection Kerish Doctor could cause a lot of issues for you including what you mentioned. The program has some features you probably shouldn't be using if you don't have some understanding of what you doing. From things I'm reading from you it seems like it's a program you shouldn't be using.

Windows 10 updates are known to have issues by itself as well as issues working with other programs. It's very possible something is conflicting with a Windows 10 update. You mentioned you tried several things with active protection.. did you disable the other active protection when you tried new one?

I want to point out the no AV is 100% and even though you are running protection that doesn't mean you don't have a virus on your pc causing the issue.

In my opinion I'd get rid of both of those programs. I don't think either of those will protect you very well let alone clean your pc of an infection. If a program doesn't do a very good job at protecting, it's very fair to say it won't do a good job a cleaning either.

As far as your net goes, just because you get 1000 Mbps doesn't mean you net can't have problems like intermittent issues. Something could be wrong with an ethernet wire or something could be wrong with your NIC or WNIC.

You mentioned your bookmarks are all white. What extensions/plugins are you running? Have you tried to reset your browser?

Do you start up from a SSD disk? Do you have enough memory on that disk? Else clean up the disk that windows is on.

Hello, check your cpu temps, my pc was really slow some time ago turns out that my cpu cooler was dead so my cpu was thermal throttling to the point that my pc was really slow but every thing was slow not just somethings so if that is the case you might have a different problem still it won't hurt to check.

Yeah I would just reboot the windows, get all your programs in google disk/clouds and any usb you have and reboot, something like this happend to my friend, but rebooting solved it all, hope you will fix it :)